Located in Matosinhos, just north of Porto, Conservas Pinhais has been putting fish in tins for more than a century. At one point, it had as many as 54 competitors, but due to overfishing and declining interest in tinned fish, they closed one by one, eventually leaving only Pinhais. Today, the factory floor can be visited via guided tour. There, you can witness how women—and only women—complete all the various tasks by hand, from gutting and preparing sardines in the ancient marble sinks to wrapping each tin with the brand’s…